st: handling missing values

Hi there,
I am working on a survey data recode and wanted to see if there is an easy
way to handle missing values. For instance, if question 1 asks whether or
not respondent used cocaine in lifetime - and the responses are yes, no,
don't know and refused. Question 2 (have you used in past 12 months -
response choices yes, no, dk, ref ) however is asked only of those who
said yes to question 1 - the no, dk, and refused responses from Question 1
are missing - - is there a quick and easy way to recode question 2 so that
it is among the total population - ie. the missing values that are a result
of respondents saying "no" to question 1 being coded into the "no" of
question 2 and the dk and refused choices from question 1 which are now
missing in question 2 - having them coded into the dk and refused of
question 2? I am currently doing this via a very convaluded method and a
colleague told me spss is much easier for handling missing values when
recoding data such as this, but I'm thinking there must be an easy way of
doing this in stata.
Thanks
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